NEW YORK (CNN) -- This past weekend, Republican Senator Chuck Grassley of Iowa, the influential chairman of the Senate Finance Committee, seemed to throw cold water on President Bush's hopes for major Social Security change. And recent polls have shown that the public is also cool to the idea of private accounts, arguably the central element of President Bush's Social Security plan.

But as the Social Security debate continues to unfold, do not underestimate President Bush's ability to still get his ideas enacted. Indeed, even without broad Congressional or public support, President Bush just may have an ace up his sleeve. How might he enact his private accounts idea without such support, you may ask? By executive order.

Indeed, the Constitution has long provided the president with a certain amount of unilateral power to make policy. And from George Washington to George W. Bush, that power has frequently been used when presidents have felt stymied by Congress or the courts. Among some of the notable presidential directives (a broader category of unilateral presidential power that includes executive orders, proclamations, pardons, national security directives and more) are: the Louisiana Purchase, the Emancipation Proclamation, and the Japanese Internment Camps.

When President Clinton failed to get his health care plan passed in the mid-1990s, he experimented with portions of his program via executive order.

Similarly, if President Bush ultimately fails to persuade Congress (especially centrist Senators) to back his private account plan, he may sign an executive order for a smaller version of his plan, such as allowing federal employees to experiment with a heavily regulated form of private accounts. It clearly would not be his first choice.

He'd rather enact a broad national plan, passed by Congress and signed by him. But if he cannot get Congressional passage of an overall Social Security change plan (or even just the private account portion), President Bush just may use the executive order route to ensure that a test version is put into effect.

And while President Clinton was sometimes criticized for his bold use of executive orders, he had to be at least somewhat politically cautious because of the risk that Congress or the courts might overturn him. President Bush has less risk in that regard because of Republican dominance in both arenas. And thus, he may indeed be more aggressive in using the executive order to implement private accounts if his legislative efforts fail.

By the way, if President Bush uses the tool to change Social Security, it will be the fourth major arena in which he has meaningfully advanced policy using presidential directives. Indeed, he has almost single-handedly created his multi-billion dollar faith-based initiative through executive orders, allowing churches and religious institutions access to taxpayer money for drug treatment, mentoring and other social service programs.

Second, as The New Yorker's Seymour Hersh and others have reported, presidential directives have guided much of the covert war on terrorism. Third, President Bush has significantly relaxed regulations and oversight of a number of large business industries via executive order.

Critics of executive orders note that Congress and the courts rarely overturn such directives, thereby raising the specter of unchecked, un-reviewed and potentially even presidential abuse of power. Indeed, the Supreme Court has only overturned an executive order twice and Congress a mere four times in the past century. Perhaps in part because of this leeway, Harvard political scientist William Howell estimates that since FDR, presidents have increased use of unilateral power in significant areas by a factor of four.

So this fall, whether the issue is Social Security or what to do in the nuclear standoffs with Iran and North Korea, keep your eyes on the ace up President Bush's sleeve.